Modular graft component junctions

ABSTRACT

The present invention embodies an endovascular graft having an attachment frame connection mechanism that allows placement of the main body component in vasculature in combination with limb components. Various limb component-to-main body component attachment mechanisms are provided which ensure a reliable bond while facilitating a smaller delivery profile.

This application is a divisional of U.S. application Ser. No.10/090,472, filed Mar. 4, 2002, which is a continuation-in-part of U.S.application Ser. No. 09/562,595, filed May 1, 2000. This applicationclaims the benefit of U.S. Provisional Application Ser. No. 60/360,323,filed Feb. 26, 2002, entitled Endovascular Grafting Device, whichcontents are incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

This invention relates to methods for delivering and deploying anendovascular graft within the vasculature of a patient and morespecifically to a modular grafting system used to treat vasculature.

It is well established that various fluid conducting body or corporeallumens, such as veins and arteries, may deteriorate or suffer trauma sothat repair is necessary. For example, various types of aneurysms orother deteriorative diseases may affect the ability of the lumen toconduct fluids and, in turn, may be life threatening. In some cases, thedamage to the lumen is repairable only with the use of prosthesis suchas an artificial vessel or graft.

For repair of vital lumens such as the aorta, surgical repair issignificantly life threatening or subject to significant morbidity.Surgical techniques known in the art involve major surgery in which agraft resembling the natural vessel is spliced into the diseased orobstructed section of the natural vessel. Known procedures includesurgically removing the damaged or diseased portion of the vessel andinserting an artificial or donor graft portion inserted and stitched tothe ends of the vessel which were created by the removal of the diseasedportion. More recently, devices have been developed for treatingdiseased vasculature through intraluminal repair. Rather than removingthe diseased portion of the vasculature, the art has taught bypassingthe diseased portion with a prosthesis and implanting the prosthesiswithin the vasculature. An intra arterial prosthesis of this type hastwo components: a flexible conduit, the graft, and the expandableframework, the stent (or stents). Such a prosthesis is called anendovascular graft.

It has been found that many abdominal aortic aneurysms extend to theaortic bifurcation. Accordingly, a majority of cases of endovascularaneurysm repair employ a graft having a bifurcated shape with a trunkportion and two limbs, each limb extending into separate branches ofvasculature. Currently available bifurcated endovascular grafts fallinto two categories. One category of grafts are those in which apreformed graft is inserted whole into the arterial system andmanipulated into position about the area to be treated. This is aunibody graft. The other category of endovascular grafts are those inwhich a graft is assembled in-situ from two or more endovascular graftcomponents. This latter endovascular graft is referred to as a modularendovascular graft. Because a modular endovascular graft facilitatesgreater versatility of matching the individual components to thedimensions of the patient's anatomy, the art has taught the use ofmodular endovascular grafts in order to minimize difficultiesencountered with insertion of the devices into vasculature and sizing tothe patient's vasculature.

Although the use of modular endovascular grafts minimize some of thedifficulties, there are still drawbacks associated with the currentmethods. Drawbacks with current methods can be categorized in threeways; drawbacks associated with delivery and deployment of theindividual endovascular graft components, drawbacks associated with themain body portion, and drawbacks associated with securing the limbportions to the main body portion.

The drawbacks of current methods of joining the limb components of amodular endovascular graft to the main graft component includedisruption of the junction over time and leakage at the connection siteof the components. The junctions conventionally used in the art maydepend upon friction between the overlapping components to hold them inplace relative to each other. In other cases, the overlapping portion ofone component may be adapted to form a frustoconical shape compatiblewith the overlapping portion of the other component. This serves toenhance the frictional connection between the components and provides adegree of mechanical joining. However, certain of these junctions reliesprimarily upon radial pressure of a stent to accomplish the joint-sealbetween the components and may be disrupted by the high shear forcesgenerated by the blood flow and shrinkage of the aneurysm sac during thenatural healing process. Once the junction between modular components ofan endovascular graft has been disrupted, blood may flow into theaneurysm sac, a condition known as “endoleak” that can causerepressurization of the aneurysm that leads to death or severe injury tothe patient.

Furthermore, even if the junction between the components is notdisrupted, leakage may still occur. The limb components used infriction-fit designs often are composed of a stent-like exoskeleton overa layer of graft material. This means that the seal is between the graftmaterial of the limb support portion of the main body component and thestent structure of the limb component. Since the stent is not a closedstructure, it is still possible for blood to leak between the limbcomponent and the main body component.

With regard to the method of joining the limb components of a modularendovascular graft to the main body component, there therefore exists aneed for structure and a method that provides a leak-proof seal thatwill not be disrupted by blood flow or physiologic remodeling over time.

The devices and methods of the present invention address these and otherneeds.

SUMMARY OF THE INVENTION

Briefly and in general terms, the present invention embodies anendovascular graft composed of individual components deliveredindividually and assembled in-vivo and methods for delivering, deployingand assembling the same.

Throughout this specification, the term “proximal” shall mean “nearestto the heart”, and the term “distal” shall mean “furthest from theheart.” Additionally, the term “ipsi-lateral” shall mean the side forexample of the limb of a bifurcated graft which is deployed using thesame path through the vasculature that was used to deploy the main bodycomponent, and the term “contra-lateral” shall mean the side for exampleof the limb of a bifurcated graft which is deployed using a second paththrough the vasculature which is catheterized after the main bodycomponent has been deployed. Furthermore, the term “inferior” shall mean“nearest to the technician”, and the term “superior” shall mean“farthest from the technician.”

In one aspect, the invention is directed toward limb components andmethods of attaching them to the main body component of an endovasculargraft that provide a leak-resistant seal between the graft material ofthe components that will not be disrupted by blood flow or physiologicremodeling over time. Two primary concepts are contemplated; attachmentvia hooks or barbs that penetrate the graft material components andmechanical attachment that does not require penetration of the graftmaterial of the components.

In a preferred embodiment of the invention, the limb component isattached to the limb portion of the main body component by a frame orself-expanding stent at the proximal or superior end of the limbcomponent that is either inside the limb component or external the limbcomponent with graft material folded over it. The limb can bemanufactured with the hooks already through its graft. When the proximalend of the limb component is inserted and deployed within the distal endof the limb support portion of the main body component, radiallyextending components in the form, for example, of hooks or barbsincorporated within the self-expanding stent penetrate the graftmaterial of the limb support portion of the main body component to forma graft-to-graft bond.

Trauma and wear on the graft material may be reduced in several ways.The limb component can have pre-fabricated holes cut in the graft thatallow the hooks and barbs to pass through, thereby reducing trauma andwear to the limb component graft.

The bond between the limb component and limb support portion of the mainbody component can be strengthened in several ways. Tufting or theplacement of fuzzy yarn on the outside of the limb component graft andinside the limb support portion of the main body component promotesblood clotting which forms a better seal. Additionally, the stent hooksand barbs can be angled caudally (toward the feet) such that the bloodflow causes better penetration of the graft material and resistance toaxial displacement of the components.

In an alternate embodiment of the invention, the limb component isattached to the limb support portion of the main body component by amechanical joint formed between the distal end of the limb supportportion and the proximal end of the limb component that utilizes thenatural blood flow in the vessel to strengthen the bond. The distal endof the limb support portion of the main body component has an innercuff, inward taper, or inner flap that is designed to receive the limbcomponent when it is deployed. Conversely, the limb component proximalend has a stent with outward protrusions, outward taper, or outer flapthat engages the inner side of the limb support portion distal end whenit is deployed. The axial pressure of the natural blood flow inside thevessel helps to maintain the joint between the components. Additionally,the distal end of the limb support portion of the main body componentmay contain a tapered inner sleeve that facilitates funneling blood flowinto the attached limb component.

In another alternate embodiment, the limb component is attached to thelimb support portion of the main body component by a radially adjustablestructure or a “lasso” that tightens around the limb component as it isdeployed within the limb support portion. The “lasso” consists of athread connected to two slip-knots; one located at the distal end of thelimb support portion of the main body component and the other locatedproximal of the first. When the proximal end of the limb component isdeployed within the limb support portion of the main body component, theradial expansion of the self-expanding frame or stent at the proximalend of the limb component causes the most proximal slip-knot on the limbsupport portion to expand, which, in turn, tightens the slip-knot at thedistal end of the limb support portion around the limb component.

Other features and advantages of the present invention will becomeapparent from the following detailed description, taken in conjunctionwith the accompanying drawings, which illustrate, by way of example, theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view, depicting a limb component and attachmentstents of the present invention with the graft material partiallyremoved to show the internal stent;

FIG. 2 is a partial perspective view of an alternate embodiment of thelimb component depicted in FIG. 1 with pre-fabricated holes for the limbattachment stent in the graft material;

FIG. 3 is a side elevation, partial cross-sectional view of a main bodycomponent already implanted at the treatment site with the limb supportportions floating freely and the limb component depicted in FIG. 1inserted in a compressed state inside one of the limb support portions;

FIG. 4 is a side elevation, partial cross-sectional view of a main bodycomponent already implanted at the treatment site with the limb supportportions floating freely and the limb component depicted in FIG. 1deployed inside one of the limb support portions;

FIG. 5 is a partial perspective view of an alternate embodiment of thelimb component depicted in FIG. 1 with the proximal end of the graftmaterial folded over the external limb attachment stent and attached tothe limb component;

FIG. 6 is a partial perspective view depicting a traditional embodimentof the main body and limb components with fuzzy yarns attached to theinternal limb attachment stent of the limb support portion and theexternal limb attachment stent of the limb component, the graft materialpartially removed to show the tufting of the limb support portioninternal stent;

FIG. 7 is a partial perspective view of an alternate embodiment of themain body and limb components of the present invention with the mainbody component limb support portion having a tapered inner layer andinternal sealing material and the limb component having an internalsupport stent and external sealing material, the graft material andsealing material partially removed to show the limb support portioninternal taper and limb component internal stent;

FIG. 8 is a view of the main body component limb support portiondepicted in FIG. 7 from the distal end;

FIG. 9 is a view of the limb component depicted in FIG. 7 from theproximal end;

FIG. 10A is a side elevation, partial cross-sectional view of a mainbody component depicted in FIG. 7 already implanted at the treatmentsite with the limb support portions floating freely and the limbcomponent depicted in FIG. 7 inserted in a compressed state inside oneof the limb support portions;

FIG. 10B is a side elevation, partial cross-sectional view a main bodycomponent depicted in FIG. 7 already implanted at the treatment sitewith the limb support portions floating freely and the limb componentdepicted in FIG. 7 deployed inside one of the limb support portions;

FIG. 11A is a partial perspective view of an alternate embodiment of themain body and limb components of the present invention where the limbsupport portion of the main body component has a “lasso” attached to thedistal end and the limb component has an internal support stent;

FIG. 11B is a partial perspective view depicting the joint formed whenthe limb component shown in FIG. 11A is deployed within the limb supportportion of the main body component shown in FIG. 11A;

FIG. 12A is a partial perspective view of an alternate embodiment of themain body and limb components of the present invention where the limbsupport portion of the main body component has a tapered portion and a“bell-bottom” distal portion with support stents and the limb componenthas an internal support stent;

FIG. 12B is a partial perspective view depicting the joint formed whenthe limb component shown in FIG. 12A is deployed within the limb supportportion of the main body component shown in FIG. 12A;

FIG. 13 is a schematic view of an alternate stent design of the presentinvention in which separate proximal and distal cell portions areconnected by cell connectors between the wishbone areas of the struts ofthe proximal and distal cell portions;

FIG. 14A is a partial perspective view depicting the proximal end of alimb component of the present invention with an external proximal stentutilizing the alternate stent design shown in FIG. 13 and held in acompressed state by a sheath that is shown as transparent;

FIG. 14B is a partial perspective view depicting the proximal end of alimb component of the present invention with an internal proximal stentutilizing the alternate stent design shown in FIG. 13 with the proximalcell portions extending beyond the proximal end of the limb componentand held in a compressed state by a sheath that is shown as transparent;

FIG. 14C is a partial perspective view depicting the “umbrella” orgrappling pattern produced when the sheath in FIG. 14B is retracteddistally to expose the upper cell portions of the stent;

FIG. 15 is a schematic partial cross-sectional view of the upper cellportions of the stent utilizing the alternate stent design shown in FIG.13 which is partially deployed and indicating pertinent dimensions;

FIG. 16A is a partial perspective view depicting the proximal end of alimb component of the present invention where the graft material isfolded over itself to provide additional support for the area wherethere is the largest separation between stent struts and the graftmaterial is partially removed to show the internal stent;

FIG. 16B is a cross-sectional view along line 16B-16B of FIG. 16A;

FIG. 17A is a partial perspective view depicting the proximal end of alimb component of the present invention with a graft material patchattached over an unattached external stent and the graft material patchpartially removed to show the stent;

FIG. 17B is a cross-sectional view along line 17B-17B of FIG. 17A;

FIG. 18A is a partial perspective view depicting the proximal end of alimb component of the present invention where the graft material isfolded over an unattached external stent and the graft material ispartially removed to show the stent;

FIG. 18B is a cross-sectional view along line 18B-18B of FIG. 18A;

FIG. 19A is a partial perspective view depicting the proximal end of alimb component of the present invention where a graft belt is attachedover an external stent;

FIG. 19B is a cross-sectional view along line 19B-19B of FIG. 19A;

FIG. 19C is a view of the limb component depicted in FIG. 19A from theproximal end;

FIG. 20A is a partial perspective view depicting the proximal end of alimb component of the present invention where two graft belts areattached over an external stent having attachment hooks or barbs;

FIG. 20B is a cross-sectional view along line 20B-20B of FIG. 20A;

FIG. 20C is a view of the limb component depicted in FIG. 20A from theproximal end;

FIG. 21A is a partial perspective view depicting the proximal end of alimb component of the present invention where the graft material isfolded over the connector eyelets of an external stent; and

FIG. 21B is a cross-sectional view along line 21B-21B of FIG. 21A;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention relates to an endovascular graft which isassembled in-vivo from components, and methods for attaching andsecuring the individual components.

FIG. 1 shows a limb component 80 that is one aspect of the presentinvention. The limb component has a proximal end 81 with a proximalstent 84, a distal end 82 with a distal stent 85, and graft material 83.The proximal stent 84 is located internal to the graft material and isself-expanding with a series of caudal hooks or barbs 86 which puncturethe graft material of the main body limb portion 33 when the stent 84 isdeployed. The proximal stent 84 is designed to be attached to a limbsupport portion 33, 34 of the main body component 30 of a bifurcatedendovascular graft (see FIGS. 3 and 4). The distal stent 85 is alsoself-expanding and is designed to be attached to the vessel wall toanchor the distal end 82 of the limb component 80. Although shownexternal to the graft material with a series of caudal hooks or barbs86, the distal stent 85 can be located internal to the graft materialand may be of any type known within the art. Note that the hooks orbarbs 86 at the proximal end 81 are angled in the distal direction,which is the direction of blood flow in the vessel. This angling helpsto ensure better attachment of the limb component 80 to the main bodycomponent 30. The barbs on the distal end 82 of the limb point oppositeto the blood flow. When the limb component 80 is compressed fordelivery, the hooks or barbs 86 of the stents 84, 85 are also at leastpartially compressed.

FIG. 2 depicts an alternate embodiment of the limb component 80 shown inFIG. 1. The limb component 180 has relief holes 87 that are spacedaround the circumference of the proximal end 81 of the graft material183 to correspond to the hooks or barbs 86. The proximal stent 84 isattached to the graft material 183 using sutures 88 such that the hooksor barbs 86 protrude through the holes 87 when the limb component 180 iscompressed for delivery, thereby preventing the compressed hook or barb86 from tearing the graft material 183. It is contemplated that reliefholes 87 may also be utilized for an internal stent 85 near the distalend 82 of the limb component 180 or whenever is desired to preventtearing of the graft material by a compressed stent having hooks orbarbs.

In a preferred embodiment, the limb component 180 proximal stent 84 iscut from a Nitinol tube using a laser beam and has five hooks 86 equallyspaced around its circumference at 72 degrees apart. The stent 84 isheat-set for its final expanded diameter using a process known in theart, with the hooks 86 set at an approximately 45 degree angle using ainner mandrel and outer cylindrical tube, the stent 84 “electropolished”, and the hooks 86 sharpened. The stent 84 is sutured insidethe limb components 180 graft material 183 which has five holes 87equally-spaced around its circumference. The holes 87, pre-puncturedusing a hot pin to melt the graft material 183, or ultrasonicallypunched, allow the five stent hooks 86 to protrude through the graftmaterial 183 when the limb component 80 is compressed for delivery. Whenthe limb component 80 is deployed within the limb support portion 33, 34of a main body component 30, the stent 84 will expand, thereby causingthe hooks 86 to penetrate the graft material of the main body component30, forming a seal and anchoring the limb component 80 within the mainbody component 30. A balloon can also be used to set the hooks. A “tug”in the distal direction can also set the hooks.

Referring to FIGS. 3 and 4, the method for joining the limb component 80to the main body component 30 is shown. With the main body component 30already implanted within the patient's vasculature 160, the limbcomponent 80 is inserted in its compressed state within one of the limbsupport portions 34 of the main body component 30. The hooks or barbs 86penetrate the limb graft before it is compressed. Once the limbcomponent 80 is positioned properly, it is deployed. When the proximalend 81 of the limb component 80 is deployed, the radial force of theproximal stent 84 causes the hooks or barbs 86 to penetrate the graftmaterial of the main body component 30 limb support portion 34, therebylocking the two components together and forming a seal between twolayers of graft material. This graft-to-graft seal resists blood leakagebetter than the traditional stent-to-graft seal. The direction of bloodflow (shown by arrow in FIG. 4) strengthens the seal by forcing the limbcomponent 80 in the distal direction, thereby imbedding the hooks orbarbs 86 in the graft material.

Furthermore, there is no pre-determined attachment point within the limbsupport portion 34 of the main body component 30. Therefore, thetechnician can position the proximal end 81 of the limb component 80anywhere within the limb support portion 34, thereby allowing him toadjust the length of the limb component 80 between the main bodycomponent 30 limb support portion 34 distal end and the limb component80 distal end 82 attachment point within the iliac “landing zone.”

Moreover, several limbs 80 can be “chained” together, allowing thetechnician to customize the length of the limb section to thevasculature of individual patients or to correct for misjudgment of thelength between the main body component 30 and the iliac “landing zone.”It is contemplated that the graft material of the main body component 30and limb component 80 can be polyethylene terephthalate (e.g. Dacron®)or PTFE (e.g. Teflon®) or any other similar material known in the art.It is further contemplated that the limb component 80 stent 84, 85material can be Nitinol, Elgiloy, stainless steel, or any similarmaterial known in the art that is either self-expanding or balloonexpandable.

FIG. 5 depicts another alternate embodiment of the limb component 80shown in FIG. 1. The limb component 380 has an external proximal stent184 with hooks or barbs 86. The proximal stent 184 is covered by thelimb component 380 graft material 83 which is folded over from a pointproximal the stent 184 and attached to itself at a point distal thestent 184, thereby forming an inner graft portion 90 and outer graftportion 91 at the proximal end 81 of the limb component 380. Hooks orbarbs 86 on the proximal stent 184 protrude through the outer graftportion 91. When the limb component 380 is deployed, the hooks or barbs86 penetrate the graft material of the main body component 30 limbsupport portion 33, 34, thereby forming a mechanical interconnectionbetween them. Although the mechanical interconnection is between thehook or barbs 86 of the limb component 380 and graft material of thelimb support portion 33, 34, the graft-to-graft contact between theouter graft portion 91 of the limb component 380 and the graft materialof the limb support portion 33, 34 provides a better seal against bloodleakage between the components than proximal stent 184-to-graft contactwould.

It is contemplated that tufting 92 can also be used where the sealbetween the limb component and main body component is achieved bytraditional methods. For example, FIG. 6 depicts a limb component 580with an external proximal stent 184 that is to be deployed within thelimb support portion 134 of a main body component 130 with an internaldistal stent 52. The seal is formed by the main body component 130internal distal stent 52 that resists the expansion of the limbcomponent 580 external proximal stent 184. Tufting 92 on the outside ofthe limb component 580 graft material 83 protrude through the externalproximal stent 184. Likewise, tufting 92 on the inside of the limbsupport portion 134 graft material protrude through the internal distalstent 52. The tufting 92 will fill spaces between the stents 52, 184 andgraft material as well as spaces between the two stents 52, 184, therebypromoting blood clotting, improving the seals, and reducing bloodleakage. The location of the stents 52, 184 in FIG. 6 is intended fordemonstration purposes only as it is contemplated that tufting 92 may beused to improve the seal anytime stents are used.

Alternately, the components may be attached without hooks or barbs whichcan lead to deterioration or tearing of the graft material. FIGS. 7-9depict one such method. The main body component 330 is defined by a limbsupport portion 334 that has a tapered inner graft layer 66 and an outergraft layer 67. The outer graft layer 67, which parallels the profile ofthe main body component 330, is further defined by a sealing material 68around the inner circumference. The sealing material 68, which may beformed of graft material or plastic, forms a pattern such as a saw-toothpattern. The tapered inner graft layer 66 is attached to the innercircumference of the outer graft layer 67 proximal the sealing material68, thereby creating a funnel for blood flow into the attached limbcomponent 680. The limb component 680 has a self-expanding internalstent 84 at its proximal end 81. The limb component 680 is furtherdefined by a sealing material 93 that is secured external the graftmaterial 83. The sealing material 93 is similar to that on the limbsupport portion 334, but with an inverse pattern.

FIGS. 10A and 10B depict the joint formed between the main bodycomponent 330 and limb component 680 using this method. The main bodycomponent 330 is deployed first in the patient's vasculature. The flowof blood (indicated by the arrow) helps to keep the tapered inner layer66 of the limb support portion 334 open. The limb component 680 isinserted and partially deployed within the outer graft layer 67 of thelimb support portion 334 such that the inner layer 66 of the limbsupport portion 334 is inside the limb component 680, but the sealingmaterial 93 of the limb component 680 does not engage the sealingmaterial 68 of the limb support portion 334. The partially-deployed limbcomponent 680 is moved distally such that the edges of its sealingmaterial 93 pattern are slightly distal the corresponding edges of thelimb support portion 334 sealing material 68 pattern and the limbcomponent 680 is then fully deployed. The flow of blood (shown by thearrow) forces the inner layer 66 of the limb support portion 334 toexpand and thereby causes the limb component 680 to advance distally.The radial expansion of the limb component 680 proximal stent 84 causesthe limb component 680 sealing material 93 to engage the limb supportportion 334 sealing material 68, thereby preventing further distalmigration of the limb component 680. The resulting mechanical jointbetween the limb component 680 and limb support portion 334 sealingmaterials 93, 68 provides better resistance to distal migration of thelimb component 680 than traditional methods, such as a frictional joint,without deterioration or tearing of the graft material 83. It iscontemplated that this method may be used to join any two componentswhere the first-deployed component has a tapered inner graft layer andan outer graft layer with sealing material on its inner surface and thesecond component, with an internal self-expanding stent and sealingmaterial external the graft material, is deployed within the firstcomponent such that the first component tapered inner layer is insidethe second component.

An alternative method of attaching components without hooks or barbs isdepicted in FIGS. 11A and 11B. The main body component 430 is defined bya limb support portion 434 which has a “lasso”. The “lasso” has aproximal loop 75, a distal loop 76, and a transition portion 77. The“lasso” may be formed by two slipknots attached or laced through thegraft material and connected by a thread or a single thread that islaced through the graft material and attached at both ends such that theloops cannot move along the axis of the graft. The “lasso” is furtherdefined by a length (indicated as L₁ In FIG. 11A). Wire, suturematerial, ribbon, rope, or string may be used instead of thread. Thelimb component 80 is defined by a self-expanding internal stent 183 atthe proximal end 81. The proximal stent 183 is further defined by aproximal end 94, a distal end 95, and an axial length (indicated as L₂in FIG. 11A). The total length of the material used to create the two“lasso” loops minus the transition length is less than twice thecircumference of the expanded limb component 80 such that expanding oneof the loops causes the other loop to constrict to a diameter less thanthat of the limb component 80. However, the total length of the materialused to create the two “lasso” loops and transition portion must besufficient to preclude the expansion of one loop from causing the otherloop to constrict so much that it occludes the limb component 80.Furthermore, the length of the “lasso” is less than the axial length ofthe limb component 80 proximal stent 183 (L₁<L₂) such that the limbcomponent 80 may be positioned and the “lasso” proximal loop 75 expandedby the deployed stent 183 proximal end 94 while the “lasso” distal loop76 constricts around the stent 183 distal end 95.

FIG. 11B depicts the joint formed between the main body component 430and limb component 80 using this method. The main body component 430 isdeployed first. The limb component 80 is delivered in a compressed stateand positioned such that the limb support portion 434 proximal loop 75is directly above the proximal end 94 of the limb component proximalstent 183 and the limb support portion distal loop 76 is directly abovethe distal end 95 of the limb component proximal stent. When the limbcomponent 80 proximal stent 183 is deployed, the radial force of theproximal end 94 causes the limb support portion 434 proximal loop 75 toexpand, thereby causing the limb support portion 434 distal loop 76 tocontract around the distal end 95 of the stent 183. The resulting jointbetween the components is both mechanical, between the radial force ofthe distal end 95 of the stent 183 and the constricted distal loop 76,and frictional, between the limb component 80 and limb support component434 graft materials. Such a joint provides better resistance to distalmigration of the limb component 80 than traditional methods, such as anentirely frictional joint, without deterioration or tearing of the graftmaterial. It is contemplated that this method may be used to join anytwo components where the first-deployed component has a “lasso”mechanism at the distal end and the second component, with a proximalsupport stent, is deployed within the first component such that theproximal end of the “lasso” is expanded by the stent while the distalend of the “lasso” constricts around the stent. Also, the entire stentcould be placed above the distal loop. Although FIGS. 11A and 11B depictan internal limb component proximal stent 183, it is contemplated thatthe stent may be located external the limb component graft material.

Another alternative method of attaching components without hooks orbarbs is depicted in FIGS. 12A and 12B. The main body component 530 isdefined by a limb support portion 534 that has a tapered middle portion78 and a “bell-bottom” distal portion 70. The limb support portion 534is further defined by an external support stent 152 located proximal thetapered portion 78 and an external “bell-bottom” stent 171. The limbcomponent 80 is defined by a self-expanding internal stent 183 at itsproximal end 81.

In a preferred embodiment, the contra-lateral limb support portion 534has a tapered middle portion 78 and “bell-bottom” distal portion 70. Thecontra-lateral limb support portion 534 external stent 152 has an axiallength of 1 centimeter and the “bell-bottom” portion 70 has an axiallength of 2 centimeters with a 0.75 centimeter “bell-bottom” stent 171at the distal end. Furthermore, the ipsi-lateral limb support portion533 has an external stent (not shown) with an axial length of 1 to 2centimeters just proximal a tapered distal end (not shown). Moreover,the contra-lateral limb support portion 534 is at least 1.5 centimeterslonger than the ipsi-lateral limb support portion 533, thereby allowingpacking of the main body component 530 without any stents occupying thesame axial space. The limb component 80 internal proximal stent 183 hasan axial length of 1 to 2 cm. All stents are made of Nitinol.

FIG. 12B depicts the joint formed between the main body component 530and limb component 80 using this method. The main body component 530 isdeployed first. The flow of blood (indicated by the arrow) and the limbsupport portion 534 stents 152, 171 keep a passageway open through whichthe limb component 80 is inserted. The limb component 80 is delivered ina compressed state and inserted into the limb support portion 534 suchthat the distal end of the limb component 80 proximal stent 183 isproximal to the limb support portion 534 tapered middle portion 78. Whenthe limb component 80 is deployed, the radial force of the proximalstent 183 forces the limb component 80 graft material 83 against thelimb support portion 534 graft material and the tapered portion 78prevents distal migration of the limb component 80. The resulting jointbetween the components is both mechanical, between the expanded stent183 and tapered portion 78, and frictional, between the limb component80 and limb support component 534 graft materials. Such a joint providesbetter resistance to distal migration of the limb component 80 thantraditional methods, such as an entirely frictional joint, withoutdeterioration or tearing of the graft material. It is contemplated thatthis method may be used to join any two components where thefirst-deployed component has a tapered middle portion and “bell-bottom”distal end and the second component, with a proximal support stent, isdeployed within the first component such that the distal end of thestent is proximal to the tapered portion. Although FIGS. 12A and 12Bdepict external limb support portion stents 152, 171 and an internallimb component proximal stent 183, it is contemplated that the stentsmay be located either internal or external the graft material.

An alternative method, known within the art, of attaching componentswithout hooks or barbs is engaging a stent attached external theproximal end of the limb component with a main body component limbsupport portion having an internal cuff or loops sewn inside the graftmaterial near the distal end. Utilizing the stent shown in FIG. 13facilitates easier mating of the limb component and limb support portionof the main body component. The stent 284 is defined by cells withseparate proximal 103 and distal 104 portions having cell connectors 159between some of the proximal wishbone areas 58 of the cells. The cellconnectors are longer than the compressed length of the proximal cellportions. Therefore, it is possible to partially deploy the proximalportions of the cell while maintaining control of the distal portion ofthe cell and cell connectors, a process which produces an “umbrella”effect.

The stent may be located external the limb component graft material 83,as shown in FIG. 14A, or the distal cell portions 104 may be locatedinternal the graft material with the proximal cell portions 103 locatedbeyond the proximal end 81 of the limb, as shown in FIG. 14B. When theproximal cell portion of the stent is uncovered but the distal cellportion of the stent is still covered, as shown in FIG. 14C, theproximal cell portion starts to deploy. Since the distal end of the cellconnectors 159 are still covered by the catheter jacket 251 and restrainthe proximal wishbone area 58 of the proximal cell portions, thedeployment is only partial and an “umbrella” or grappling hook shaperesults. By maneuvering the catheter inner member 216, the distalwishbone area 105 of the partially deployed proximal cell portion 103may be mated with a cuff or other attachment mechanism (not shown) of alimb support portion of the main body component. Once proper engagementof the limb component and limb support portion is verified, eithervisually seeing the limb support component move or feeling a tug oncethe distal wishbone area 105 engages the attachment mechanism, thecatheter jacket 251 is retracted distally to fully deploy the proximal103 and distal 104 cells portions of the stent.

It is contemplated that the “umbrella” stent 284 may be permanentlyattached to a catheter and utilized as a snare to retrieve clots orpieces of medical devices such as coils, catheter tips, or guidewires.It is also contemplated that an umbrella stent 284 having sharpeneddistal wishbone areas 105 may be utilized to anchor a graft to the wallsof a vessel.

The minimum length of the proximal cell portions (indicated as L in FIG.15) is a function of the catheter inner member 216 outer diameter(indicated as COD in FIG. 15), the limb support portion 34 or lumen 160inner diameter (indicated as LID in FIG. 15), and angle at which thecell portions expand (indicated as φ in FIG. 15). The relationship isshown by the formula:ΔD=LID−CODL=(ΔD/2)/SIN φ)

In order to provide the grappling effect in both axis, at least 3 cellconnectors are provided. Although the figures show 3 cells between cellconnectors, it is contemplated that there may be any number of cellsbetween cell connectors. It is further contemplated that any cellpattern and size, as well as cells with sharp or smooth lower wishboneportions 105 may be used as long as adequate expansion is achieved andthe attachment site is adequate to accommodate the cells.

Whether the limb attachment methods of the present invention or methodsknown within the art are utilized, the manner in which the stents areattached to the graft material may effect the strength or fluid seal ofthe joint between the limb support portion and limb component. Byproviding additional graft material in areas where the stent-to-graftattachment is prone to leaks or wear as well as enabling the attachedstent to move relative to the graft material may result in a betterjoint.

FIGS. 16A and 16B show a limb component 780 with a self-expandinginternal proximal stent 84 attached to the proximal end 81 of the graftmaterial 83 with sutures 88 at only the most proximal and most distalends of the stent such that an additional layer of graft material isformed where the stent has its widest opening between struts. This isthe area most susceptible to the “parachute” effect caused when bloodleaks between the joint formed between a proximal limb stent and mainbody component limb support portion distal stent, whereby the bloodcollects in the largest graft-to-graft area in the frame stent openingsand fills like a parachute. The additional graft material in this arearesists the tendency of blood to collect. The additional area of graftmaterial may be formed by attaching the most proximal or most distal endof the stent to the graft material with sutures and pulling the graftmaterial inside itself to form an overlapping area 100 before attachingthe other end of the stent to the graft material, thereby forming a foldof graft material around the circumference of the graft material whichtraverses the widest area between stent struts. It is contemplated thatan additional area of graft material may also be utilized for the mainbody component limb support portion distal stent or for any type ofvessel repair that requires an implant seal.

Providing a graft pocket within which a self-expanding external stentwithout attachment hooks or barbs may move is one way to facilitate abetter joint between the limb support portion of the main body componentand the limb component. The stent, which is not attached to the graftmaterial, moves proximally or distally within the pocket, therebyfacilitating self-alignment after deployment. The ability to self-alignprovides a more secure joint. It is contemplated that a graft pocket maybe used for a main body component limb support portion distal stent,limb component proximal stent, or whenever it is desired to attach aself-expanding stent or frame to a graft type material for human vesselrepair.

A graft pocket may be formed by attaching additional graft material.FIGS. 17A and 17B show a limb component 880 with a self-expandingexternal proximal stent 184 and an additional graft ring patch 249attached to the proximal end 81 of the graft material 83, therebycovering the external stent. The graft ring patch, which is attached bysutures 88 at its proximal and distal extremities, forms a pocket withinwhich the stent may move. It is contemplated that the graft ring patchmay be attached with a continuous stitching pattern around the entirecircumference of the graft, rivets or other methods known within the artrather than with individual sutures. It is also contemplated that agraft ring patch may be attached to the distal end of the main bodycomponent limb support portion.

Alternately, a graft pocket may be formed without attaching additionalgraft material. FIGS. 18A and 18B show a pocket formed by pulling theproximal end of the limb component 380 graft material 83 distally overthe external self-expanding proximal stent 184 and attaching it to thegraft material distal the stent. In a preferred process, the proximalstent is covered by the limb component graft material, thereby forming apocket between an inner graft portion 90 and outer graft portion 91 atthe proximal end 81 of the limb component. Attachment of the graftmaterial distal the enclosed stent may be by sutures 88, a continuousstitch around the graft, rivets or other methods known within the art.It is also contemplated that the graft fold-over may be used at thedistal end of the main body component limb support portion.

Instead of providing a graft pocket, additional strips of graft materialattached to the external surface of the graft material may be utilizedto facilitate stent self-alignment without completely enclosing thestent in graft material. It is contemplated that additional strips ofgraft material that hold self-expanding stents in place may be utilizedwhether or not the stent has attachment hooks or barbs. It is alsocontemplated that additional strips of graft material may be used for amain body component limb support portion distal stent, limb componentproximal stent, or whenever it is desired to attach a self-expandingstent or frame to a graft type material for human vessel repair.

As shown in FIGS. 19A, 19B and 19C, a single strip of graft material maybe used with a stent having no attachment hooks or barbs. The limbcomponent 980 with a self-expanding external proximal stent 184 is heldin place by a strip of graft material 101 that traverses thecircumference of the proximal end 81 of the graft material 83. The stripof graft material 101, which is attached by sutures 88 such that loops102 are formed within which the stent struts may move, may be thicker orthinner than the limb component graft material 83. It is contemplatedthat the strip of graft material 101 may also be attached by rivets orother methods known within the art.

Alternately, two strips of graft material may be used with a stenthaving attachment hooks or barbs. FIGS. 20A, 20B and 20C show a limbcomponent 980 with a self-expanding external proximal stent 184 havingattachment hooks or barbs 86 and two strips of graft material 101 thattraverse the circumference of the proximal end 81 of the graft material83. The strips of graft material 101, which are attached by sutures 88such that loops 102 are formed within which the stent struts may move,may be thicker or thinner than the limb component graft material 83. Thestrips of graft material 101 are attached above and below the attachmenthooks or barbs 86, thereby precluding tangling.

Providing additional protection at the areas where stents or other metalcontact graft material may decrease wear and increase reliability ofendovascular graft components. Sites that are susceptible to wear, andhence would benefit from such protection, include frame attachmentsites, areas where hooks or barbs penetrate the graft material, andareas of friction or motion between metal features and graft material.

One way to reinforce graft material sites susceptible to wear is toreinforce the graft fabric. A coating, such as a thin coat of abiocompatible elastomer can be screen printed or otherwise applied in aband around the graft.

Coating the entire surface of the graft material may be preferred,particularly if ultra thin woven PET graft material is used to reduceimplant bulk. As the thickness of the graft material is reduced, thepermeability increases. Coating the entire surface of the graft materialnot only increases reliability of the graft but also reducespermeability without increasing bulk. A polyurethane co-polymer coatingmay be dip-coated onto the woven PET substrate. When the solvent isremoved, a biocompatible, non-thrombogenic surface to contact thearterial blood is left bonded to the PET material. The thickness of thecoating may vary from a few to many microns. It is contemplated thatmultiple dipping and drying steps may be performed to produce a thickercoating to meet permeability requirements.

Alternately, the weave pattern of the graft material may be altered incertain regions to provide extra strength where needed. A rip stop typegraft material weave is one example of a typical graft reinforcementmethod.

An alternate way to reinforce areas of the graft susceptible to wear isto provide an additional layer of graft material. FIGS. 21A and 21B showa limb component 380 with the graft material folded over to provideadditional reinforcement for the site where a self-expanding externalproximal stent 184 is attached to the graft material 83. In a processsimilar to that shown in FIGS. 18A and 18B, a pocket is formed betweenan inner graft portion 90 and outer graft portion 91 at the proximal end81 of the limb component into which the proximal eyelets of the stentare placed. The stent is attached using sutures 88 which are sewnthrough the eyelets and the double layer of graft material, therebyincreasing the durability of the joint. Additionally, a running stitch65 similar to that defined for connection of the main body attachmentstent may provide further reinforcement of the suture joint. It iscontemplated that the graft fold-over may be used to attach an internalproximal stent by folding the graft material inside rather than outsidethe original graft material layer. It is further contemplated that thegraft fold-over may be used to attach a stent to the distal end of themain body component limb support portion or whenever a stent is attachedwith sutures to graft material.

Although the various attachment mechanisms are depicted with respect tothe contra-lateral limb component, it is to be noted that this is donefor demonstration purposes only. It is contemplated that the attachmentmechanisms depicted may be applied to attach the ipsi-lateral limbcomponent of a bifurcated endovascular graft as well as to attach anytwo modular endovascular graft components. It is further contemplatedthat the various attachment mechanisms depicted herein may be swapped.For example, the attachment mechanism depicted as part of the limbcomponent may be provided as part of the main body component and theattachment mechanism depicted as part of the main body component may beprovided as part of the limb component.

Thus, it will be apparent from the foregoing that, while particularforms of the invention have been illustrated and described, variousmodifications can be made without the parting from the spirit and scopeof the invention. For example, both the main graft component and thelimb components can have various configurations including tubular,flared, bifurcated and trifurcated forms. Accordingly, it is notintended that the invention be limited, except as by the appendedclaims.

1. A modular graft device for treating vasculature, comprising: a firstgraft component configured with at least one receiving element radiallyextending inward; a second graft component with a proximal end to beinserted into an orifice of the first graft component comprising a stenthaving at least one component radially extending outward that engagesthe at least one receiving element of the first graft component; and amechanical joint between the first and second graft components, themechanical joint having structure such that the bond between the firstand second graft components is strengthened as the longitudinal load onthe mechanical joint increases.
 2. The modular graft device of claim 1,wherein the first and second graft components are mechanicallyinterconnected by the at least one radially extending component beingembedded in the first graft component when inserted into the orifice. 3.The modular graft device of claim 1, the mechanical joint furthercomprising an inner cuff attached to the first graft component.
 4. Themodular graft device of claim 1, the mechanical joint further comprisingan inward taper attached to the first graft component.
 5. The modulargraft device of claim 1, the mechanical joint further comprising aninner flap attached to the first graft component.
 6. The modular graftdevice of claim 1, wherein one of the first or second graft componentsis flared.
 7. The modular graft device of claim 1, the mechanical jointfurther comprising an outward protrusion attached to the second graftcomponent.
 8. The modular graft device of claim 1, the mechanical jointfurther comprising an outward taper attached to the second graftcomponent.
 9. The modular graft device of claim 1, the mechanical jointfurther comprising an outer flap attached to the second graft component.10. The modular graft device of claim 1, the first component furthercomprising a tapered sleeve that facilitates funneling of blood to thesecond graft component.
 11. The modular graft device of claim 1, whereinthe first graft component is bifurcated.
 12. The modular graft device ofclaim 1, further comprising at least one self-expanding stent which isoperatively associated with the mechanical joint.
 13. A modular graftdevice for treating vasculature, comprising: a first graft componentconfigured with a radially adjustable structure and at least onereceiving element radially extending inward; and a second graftcomponent with a proximal end to be inserted into an orifice of thefirst graft component comprising a stent having at least one componentradially extending outward that engages the at least one receivingelement of the first graft component, which when placed in contact withthe first graft component, causes the radially adjustable structure toaccomplish an attachment between the first graft component and thesecond graft component.
 14. The modular graft device of claim 13, theradially adjustable structure further comprising a thread.
 15. Themodular graft device of claim 14, wherein the thread is configured intoa form of a lasso.
 16. The modular graft device of claim 15, the lassofurther comprising a plurality of slip knots.
 17. The modular graftdevice of claim 15, the lasso further comprising a first slip knot and asecond slip knot positioned proximal the first slip knot.
 18. Themodular graft device of claim 17, the second graft component furthercomprising a self-expanding frame which causes a slip knot to tightenwhen the frame expands.
 19. The modular graft device of claim 18,further comprising at least one expandable frame attached to the firstgraft component.
 20. The modular graft device of claim 18, furthercomprising at least one expandable frame attached to the second graftcomponent.
 21. The modular graft device of claim 13, wherein the firstgraft component is bifurcated.
 22. The modular graft device of claim 13,wherein the second graft component has a generally tubularconfiguration.